Recently, it has been known to equip a theft tracking device to an object, such as a motorcycle and a navigation device, for tracking the object when the object is stolen. The theft tracking device transmits information on, a current position of the object when the object is stolen. Such a theft tracking device is, for example, described in JP2011-51376A.
The theft tracking device includes a circuit board and a back-up battery. The circuit board performs operations to specify a current position of the theft tracking device through a global positioning system (GPS), a vehicle information and communication system (VICS) or the like, and to transmit the information specified through a wireless communication. The back-up battery supplies electric power to the circuit board.
FIG. 9 illustrates a theft tracking device 100 for a motorcycle, as an example. The theft tracking device 100 includes a back-up battery (BUB) 102, a battery case 101, a circuit board 103, a housing body 110 and a housing cover 111. The battery case 101 has an opening at its bottom, and the BUB 102 is housed in the battery case 101. The battery case 101 is fixed to the circuit board 103 and is disposed in the housing body 110 in a state of being fixed to the circuit board 103.
In the theft tracking device 100, the housing body 110 has an opening for installing the components, such as the BUB 102, inside of the housing body 110. The opening of the housing body 110 is covered with the housing cover 111. In FIG. 9, the housing cover 111 is illustrated as transparent for a purpose of showing the inside of the housing body 110. Also in FIG. 10, the housing cover 111 is illustrated as transparent for the similar purpose.
In a case where a circuit board and a back-up battery are housed in the same housing body, if a battery liquid leaks from the back-up battery due to vibration of the motorcycle, the battery liquid will adhere to the circuit board.
If the battery liquid adheres to the circuit board, the circuit board may be corroded from a portion to which the battery liquid is adhered, resulting in a failure in operation of the circuit board.
To address such an issue, in the theft tracking device 100 of FIG. 9, the battery case 101 has the opening at its bottom, and the BUB 102 is received in the battery case 101 such that a bottom portion of the BUB 102 exposes from the bottom of the battery case 101. Further, the circuit board 103 is arranged above the battery case 101.
In such an arrangement, even if the battery liquid leaks from the BUB 102, the battery liquid accumulates on a bottom wall of the housing body 110. Further, even if the battery liquid accumulated jumps due to the vibration, it is less likely that the battery liquid accumulated on the bottom wall will reach the circuit board 103.
To further restrict the adhesion of the battery liquid to the circuit board 103, it is considered to cover the entirety, of the BUB 102, except for the end, with the battery case 101, as shown in FIG. 10. In this case, the end of the BUB 102 is not covered with the battery case 101 because the battery case 101 has an opening for installing the BUB 102 into the battery case 101.
Namely, the battery case 101 covers the bottom portion of the BUB 102. In such a case, however, the thickness of the housing body 110, such as a dimension in an up and down direction in FIG. 10, increases as compared with the housing body 110 in which the battery case 101 does not cover the bottom portion of the BUB 102 (e.g., FIG. 9). As a result, the overall size of the theft tracking device 100 is likely to increase.
As another example of restricting the adhesion of the battery liquid to the circuit board 103, a structure shown in FIG. 11 is considered. In the structure shown in FIG. 11, similar to a battery of a cell phone, the BUB 102 is attached to the outside of the housing body 110. Further, the battery case 101 is fixed to the housing body 110 to cover the BUB 102.
In such a case, however, the position of the BUB 102 will be easily found from the outside of the housing body 110. Therefore, the BUB 102 will be easily removed from the housing body 110 when the theft tracking device. 100 is stolen. As a result, the circuit board 103 will not perform properly.